Biomedical subjects

Q Chen

Publications and source records attributed to Q Chen.

At least 433 records · Page 24Linked to original sources

PubMed1998

[Efficacy of beta-carotene on lipid peroxidation induced by N-nitrosodimethylamine in rats].

The effect of beta-carotene (beta-C) on lipid peroxidation induced by N-nitrosodimethylamine (NDMN) in rats was studied. Thirty clear conventional SD rats were randomly devided into 3 groups and were intragastricly given daily water (10 ml/kg). NDMN (1.75 mg/kg), and NDMN (1.75 mg/kg) plus beta-C (25 mg/kg) respectively. The results showed that: compared with group 1, the activities of SOD and GSH-Px in NDMN group were significantly decreased (P < 0.05), the values of MDA and ROOH increased (P < 0.05). The activities of SOD and GSH-Px in group 3 were significantly higher and the contents of ROOH and MDA were significantly lower than that of NDMN group (P < 0.05). These results suggested that free radicals and lipid peroxidation may be a carcinogenic path for NDMN and other nitrosamines. beta-C had ability to inhibit the lipid peroxidation induced by NDMN.

Animals↗

PubMed1998

[The inhibitory effect of wild-type p53 gene on the growth and proliferation of lingual squamous cell carcinoma cell line Tca8113 in nude mice].

The aim of this study was to observe the growth and proliferation of the Tca8113 cell line in nude mice after the wild-type p53 gene has been transfered by electroporation. The experiment consisted of four groups: the wild-type p53 gene, blank control plasmid, the mutant p53 gene, and blank control into which no gene was transfered. After the gene was transfected, the cells were planted into 16 nude mice respectively. When the tumor formed, the nude mice were killed and the tumors were studied by regular pathology, stereology and immunohistochemistry. The results showed that in the wild-type p53 gene group, the tumors weighed less heavy, the pathological mitosis decreased markedly, and stereologically, the ratio of the area of necrosis to the total tumorous area was smaller. Similarly, the count of the proliferation cell nuclear antigen in non-necrotic area went down. The above findings were statistically significant (P < 0.05). These indicate that when the tumor cells re-obtain the well functional exogenic wild-type p53 gene, the gene expresses and produces new negative cell-growth regulator to replace the abnormal regulation system partially, then the growth and proliferation of the tumors can be inhibited; therefore, it is suggested that the p53 tumor suppressor gene may possibly be used as a gene therapy agent to treat oral squamous cell carcinoma.

Animals↗

PubMed1998

[Changes of hemodynamics, oxygen delivery and oxygen consumption during anesthesia induction with propofol in patients with rheumatic mitral stenosis].

Changes of hemodynamics, oxygen delivery and consumption were studied in 20 patients with rheumatic mitral stenosis, undergoing mitral valve replacement, anesthesied induction with propofol(Group P) or midazolam(Group M). The results showed that hemodynamic values were decreased after intravenous propofol, and recovery after tracheal intubation. Hemodynamic values also decreased and last to 2 min after tracheal intubation in Group M. The reduction degree of HR in Group P were more, the degree of SVRI,. LVSWI, RVSWI less than those in Group M respectively. Oxygen consumption decreased more than delivery. It is suggested that induction of anesthesia with propofol in patients with rheumatic mitral stenosis is safe, and may be advantageous than midazolam.

Adolescent↗

PubMed1998

[Effects of propofol and etomidate on cerebral oxygen supply and demand balance during middle hypothermia cardiopulmonary bypass].

UNLABELLED: Effects of propofol(Group P) and etomidate(Group E) on cerebral oxygen supply and demand balance during middle hypothermia cardiopulmonary bypass(CPB) were studied in twenty patients undergoing cardiac valve replacement. Arterial blood and jugular bulb blood were taken to analyse blood gas, and cerebral oxygen content were caculated. RESULT: During hypothermia, jugular bulb oxygen saturation(SjO2), jugular bulb blood oxygen content(CjO2) increased; cerebral oxygen extraction rate(CEO2) decreased significantly in two groups(P < 0.05). During rewarming SjO2, CjO2 were significantly decreased, CEO2 increased compared with that before rewarming and hypothermia in two gbroups (P < 0.05). In Group P, SjO2 and CjO2 were higher, CEO2 lower than those in Group E respectively during rewarming (P < 0.05). CONCULUSION: The activity of propofol reduced cerebral metabolism, cerebral oxygen consumption and CEO2 is better than that of etomidate.

Adult↗

PubMed1998

[Mathematical diagnosis of idiopathic-hypoparathyroidism].

The present study devotes to diagnose idiopathic-hypoparathyroidism (IHP) by means of ratio of calcium and phosphorus and product of calcium and magnesium. Among 23 cases of IHP patients the coincidence of ratio (Ca/P) and low-calcium/high-phosphorus in blood was 95.7%. Among 17 cases of IHP patients the coincidence of product (Ca x Mg) low-calcium and low magnesium was 91.4%. It indicates that ratio (Ca/P) and product (Ca x Mg) are effective mathematical diagnosis of IHP.

Adolescent↗

PubMed1998

[Modified lipoproteins in atherosclerotic lesions of human aorta].

OBJECTIVE: To study the distribution patterns, amount, as well as the physical and chemical properties of malondialdehyde (MDA) and 4-hydroxynonenal (HNE) modified apolipoprotein B (apo B) in atherosclerotic lesions of human aorta. The distribution patterns of MDA and HNE modified apo B were also compared with those of lipoprotein(a) [LP(a)] and apo B. METHODS: Immunohistochemistry, electronic microscopy, immunoelectronic microscopic and biochemistry methods were used for qualitative and quantitative analysis. RESULTS: It was found that the distribution of MDA and HNE modified apo B coincided with Lp(a) and apo B in the extracellular matrix. While the distribution of MDA-apo B and HNE-apo B in foam cells appeared annular or particulate, similar to ceroids but different from that of Lp(a) or apo B. The physical and chemical properties of LDL from lesions on the intima were similar to those of in vitro modified LDL. In addition, a higher level of aldehyde modified LDL was extracted from the lesion areas than from normal intima. CONCLUSION: Oxidative modification of apo B containing lipoproteins is necessary for atherogenesis.

Aorta, Thoracic↗

PubMed1998

Mitochondrial gene defect in patients with chronic progressive external ophthalmoplegia.

OBJECTIVE: To detect the gene defect of mitochondrial DNA (mtDNA) from skeletal muscles in 2 patients with chronic progressive external ophthalmoplegia (CPEO). METHODS: After extraction of mtDNA, Southern hybridization was performed after restrictive digestion by Pvu II, EcoRI, Hind III, and Sacl. Then, we carried out polymerase chain reaction (PCR) and the enzyme digestion of the PCR products. Finally, mtDNA sequencing was done by automatic DNA sequence analyzer. RESULTS: In case 1, a 5 kb deletion was found by Southern blot analysis and PCR. And dosage analysis showed a heteroplasmic change with 44% mtDNAs deleted. In case 2, PCR plus restriction endonuclease Pvu II digestion demonstrated a mutation which was confirmed by DNA sequencing to be a single base substitution (T-->C) inducing a novel Pvu II site around 10,909 on mtDNA sequence. The laser image analyzer measurement revealed the mutation was almost homologous (99.4% mutant). CONCLUSIONS: In case 1, a 5 kb deletion found in mtDNA is called "common deletion" according to the literature. In case 2, a novel Pvu II site was found. It seems to be a de novo point mutation affecting ND4 in published CPEO research and is first reported in Chinese population. This point mutation does not induce an amino acid(Phe) change according to the published human mitochondrial genetic code as well as the mtDNA sequence. Whether it affects the translation efficiency or transportation of signals between mitochondrial and nuclear genome needs further studies.

Adult↗

PubMed1998

[Inhibitory activity of azithromycin on biofilm synthesis and synergism between azithromycin and fleroxacin on Pseudomonas aeruginosa in biofilms].

OBJECTIVE: The influence of azithromycin (AZT) on the production of glycocalyx (GLX) from P. aeruginosa biofilms and synergism of antibacterial activities between AZT and fleroxacin (FLX) on P. aeruginosa were investigated. METHOD: GLX production was measured by using a L-tryptophan method and viable counts in biofilms was determined by using a methylthiazolyldiphenyltetrazolium(MTT) method. RESULT: GLX production was reduced significantly from 28.0 +/- 8.1 micrograms/ml at 0MIC to 21.8 +/- 8.2 micrograms/ml at 1/16MIC and 16.7 +/- 7.9 micrograms/ml at 1/4MIC respectively (P = 0.0002). 1/16MIC and 1/4MIC AZT showed no bactericidal activities to P. Aeruginosa in biofilms. Viable counts in biofilms were 6.2 +/- 0.61 Lg/cm2 at 0MIC, 6.1 +/- 0.4 Lg/cm2 at 1/16MIC and 6.2 +/- 0.4 Lg CFU/cm2 at 1/4 MIC respectively (P = 0.63). However, AZT could enhance bactericidal activity of FLX on P. aeruginosa in biofilms. When 1/4MIC FLX was combined with 1/16MIC and 1/4 MIC AZT, viable counts were reduced significantly from 6.1 +/- 0.5 Lg CFU/cm2 to 5.9 +/- 0.3 Lg CFU/cm2 and 5.8 +/- 0.4 Lg CFU/cm2 respectively (P = 0.02). When 1/2MIC FLX was combined with 1/16MIC and 1/4MICAZT, viable counts were reduced significantly from 6.3 +/- 0.7 Lg CFU/cm2 to 5.8 +/- 0.5 LgCFU/cm2 and 5.7 +/- 0.6 Lg CFU/cm2 respectively (P = 0.03). CONCLUSION: Because AZT did not have direct bactericidal activities on P. aeruginosa in biofilms but could inhibit GLX production, We considered that AZT could enhance antibacterial activities of FLX by enhancing permeability of FLX into biofilms.

Anti-Bacterial Agents↗

PubMed1998

[Rapid determination of active constituents in compound ibuprofen tablets by capillary zone electrophoresis].

A rapid capillary zone electrophoresis (CZE) method for the determination of ibuprofen and pseudoephedrine hydrochloride in compound ibuprofen tablets has been developed. CZE was performed in 0.025 mol/L phosphate buffer solution (pH 8.1). The two compounds were completely separated within 3 minutes, and quantified with a UV-detector at 210 nm by means of external standard method. Relative standard deviations of 2.9% for pseudoephedrine hydrochloride and 1.9% for ibuprofen were achieved for 11 determinations of the sample solution containing 9.5 mg/L pseudoephedrine hydrochloride and 66.7 mg/L ibuprofen, and recoveries of 103.1% and 97.6% were obtained respectively for the spiked pseudoephedrine hydrochloride and ibuprofen. The proposed method has been applied for the analysis of compound ibuprofen tablets, and the analytical results are in good agreement with those obtained by HPLC method.

Drug Compounding↗

PubMed1998

[Relationship between hematocrit (Hct) and cardiac systolic time intervals (STI) in residents at 4300 m altitude].

In order to study the relationship between Hct and cardiac systolic time intervals (STI) in residents at high altitude, STI and cardiac function were determined by electrical impedance and carotid arteriogram in 113 subjects with different Hct at an altitude of 4300 m. There was a negative correlation between Hct and SV or EF (r = -0.841 and -0.628), respectively (P < 0.001). With increase of Hct there were prolonged pre-ejection period (PEP), shortened left ventricular ejection time (LVET), and increased PEP/LVET. SV, CO were lower in high altitude polycythemia (HAPC) than in the control (P < 0.05). It demonstrated that there is a close relationship between STI and Hct, and excessive polycythemia is one of the important factors that cause decrease of cardiac function decreasing in high altitude residents.

Adolescent↗

PubMed1998

[Immunologic and clinical study of paraneoplastic limbic encephalitis].

OBJECTIVE: To probe into the pathogenic mechanisms of paraneoplastic limbic encephalitis (PLE) in patients with small cell lung carcinoma (SCLC). METHODS: The indirect immunoperoxidase method and Western blot analysis were used for detecting anti-Hu antibodies in 16 PLE patients associated with SCLC. Autopsy and pathological study were performed on two cases. RESULTS: Eight patients (50%) had anti-Hu antibodies (anti-Hu+) whereas eight patients (50%) no detectable antineuronal antibodies (anti-Hu-). The clinical and laboratory features of PLE and time to diagnosis of SCLC were similar in the anti-Hu+ and anti-Hu- groups. Involvement of other areas of the nervous system in seven (87.5%) patients of the anti-Hu+ group but in only one (12.5)% of the anti-Hu- group (P = 0.012). CONCLUSIONS: The presence of this characteristic neurological disorder strongly suggested that with an accompanying SCLC, existence of anti-Hu autoantibody was in favour of an autoimmune mechanism participating in PLE.

Antibodies, Antinuclear↗

PubMed1998

[Coexisting pheochromocytoma and renal artery stenosis].

OBJECTIVE: To improve the diagnosis of coexisting pheochromocytoma and renal artery stenosis. METHOD: Four patients with coexisting pheochromocytoma and renal artery stenosis were treated. RESULT: After removal of the pheochromocytoma, the blood pressure became normal in two patients combined with resection of kidney with renal artery stenosis, and one patient with local adhesion loosened. The hypertension, however, persisted in another patient after the resection of pheochromocytoma even though the long segment of renal artery stenosis was relieved. CONCLUSION: After pheochromocytoma was diagnosed with its known position, coexisting renal artery stenosis should be suspected according to one of the following conditions: (1) Vascular murmurs are noted at the area of the upper abdomen or back; (2) One of the kidneys becomes less sized; (3) Using the inhibitor of receptor alpha only has no effect lowering blood pressure and it is necessary to add the inhibitor of angiotension; (4) Postoperative hypertension does not resolve when no remaining pheochromocytoma is present. the renal artery stenosis can be reversed after both removal of pheochromocytoma and loosening of adhesion in case of stenosis due to the pressure of the tumor and adhesion caused renal artery angling and local stricture. Extensive stenosis or closure, however, can not be corrected with severe atrophy of renal parenchyma due to pheochromocytoma, and the resection of kidney should be indicated.

Adolescent↗

PubMed1998

[Hemorrheologic analyses of anterior ischemic optic neuropathy].

OBJECTIVE: To find the pathogenic factor of non-temporal arteritis anterior ischemic optic neuropathy (AION). METHODS: Several items of hemorheology in 39 cases (19 males and 20 females) of acute non-temporal arteritis AION at papilloedema stage were examined and compared with that of the control group including normal comparable 20 males and 20 females. RESULTS: The results showed that hematocrit (HCT), fibrinogen, low shearing viscosity, aggregation index, erythrocyte electrophoresis time were higher in the AION group than that of the control group (P < 0.01 or P < 0.05). Besides, high shearing viscosity and plasma viscosity in the female patient group are also higher than that of the control group (P < 0.01). CONCLUSION: The high blood viscosity is closely related to the pathogenesis of non-temporal arteritis AION.

Blood Viscosity↗

PubMed1998

[Preparation of 5-fluoruracil-poly-alpha, beta(2-hydroxyethy1)-DL-asparamide and in-vivo release in rabbit].

A polymer release drug was prepared by poly-alpha, beta-(2-hydroxyethyl)-DL-asparamide(PHEA) and 5-fluorouracil. As a model drug 5-fluorouracil was conjugated into the biodegradable polymer by chemical bond. The released drug was determined to be about 37.1% (w/w) and it was characterized by IR spectrum and differential scanning calorimetry (DSC). Two forms of drugs, rod and suspension were prepared and in vivo release experiment were carried out in rabbits. The experimental result showed that the rod form of drug can in some degree reduce initial burst.

Animals↗

PubMed1998

[Respective determination of inorganic germanium and germanium-132 in foods].

Inorganic germanium and carboxyethyl germanium sesquioxide (germanium-132) in health drinks were respectively determined by hydride generation-atomic fluorescence spectrometry (HG-AFS). The conditions of respective determination of inorganic germanium and germanium-132 in natural foods were preliminarily discussed.

Beverages↗

PubMed1998

Turbo spin-echo diffusion-weighted MR of ischemic stroke.

PURPOSE: Our objective was to determine whether a multisection technique, diffusion-weighted half-Fourier single-shot turbo spin-echo (HASTE) imaging, can compensate for the drawbacks common to other diffusion-weighted techniques; specifically, the need for echo-planar technology and the presence of susceptibility artifacts in areas close to the skull base. METHODS: Forty subjects who were referred to the stroke service with signs of acute (less than 24 hour) neurologic dysfunction were included in this prospective study. MR imaging of the brain was performed with diffusion-weighted echo-planar and diffusion-weighted HASTE sequences. The images obtained with both sequences were analyzed for the presence of hyperintensities corresponding to ischemic lesions as well as for the presence of image artifacts and distortions. RESULTS: Diffusion-weighted HASTE images showed areas of hyperintensity corresponding to the infarcts present on diffusion-weighted echo-planar imaging studies without distortion or susceptibility artifacts in all the patients who had a stroke. Twelve patients had no acute ischemic lesions; of these, five had other findings, six had normal findings, and in one patient, a hyperintensity seen on diffusion-weighted echo-planar images proved to be an artifact on diffusion-weighted HASTE images. CONCLUSIONS: Diffusion-weighted HASTE is equal to diffusion-weighted echo-planar imaging in the detection of early ischemia. Because of the absence of significant image distortions and other artifacts, diffusion-weighted HASTE permits fast multiplanar imaging in artifact-prone regions, such as the posterior fossa and the inferior frontal and temporal lobes. Diffusion imaging can be performed on conventional systems with strengths of 1.5 T that do not have echo-planar imaging capabilities.

Acute Disease↗

PubMed1998

Mechanism of gallbladder relaxation in the cat: role of norepinephrine.

We investigated the mechanisms of neurally mediated relaxation of cat gallbladder muscle. Muscle strips from the gallbladder corpus placed in the muscle bath with oxygenated Krebs' solution developed spontaneous active tension. Tension was measured with isometric force transducers, and muscle relaxation was expressed as percent decrease of active basal tension. Electrical field stimulation (EFS) evoked a tetrodotoxin-sensitive and hexamethonium-insensitive frequency-dependent relaxation with a maximal relaxation at 20 Hz. Gallbladder muscle strips also relaxed in response to increasing concentrations of vasoactive intestinal peptide (VIP), isoproterenol and, after pretreatment with phentolamine, norepinephrine. Nitric oxide synthase inhibitors N omega-nitro-L-arginine and N omega-nitro-L-arginine methyl ester at a concentration of 100 microM, which blocked EFS-induced relaxation in the lower esophageal sphincter, had no significant effect on EFS-induced gallbladder muscle relaxation. The VIP antagonists VIP10-28 and [4Cl-D-Phe6,Leu17]VIP at a concentration of 10 microM that blocked exogenous VIP-induced gallbladder relaxation also had no effect on the relaxation caused by EFS. In contrast, either propranolol or guanethidine at concentrations of > or = 1 microM significantly reduced EFS-evoked gallbladder relaxation (P < .01, analysis of variance). It is concluded that norepinephrine utilizing beta adrenergic receptors mediates EFS-stimulating postganglionic intramural neurons in the cat gallbladder.

Animals↗

PubMed1998

Cytotoxicity and apoptosis produced by arachidonic acid in HepG2 cells overexpressing human cytochrome P-4502E1.

The goal of the current study was to evaluate the effects of arachidonic acid, as a representative polyunsaturated fatty acid, on the viability of a HepG2 cell line, which has been transduced to express human cytochrome P4502E1 (CYP2E1). Arachidonic acid produced a concentration- and time-dependent toxicity to HepG2-MV2E1-9 cells, which express CYP2E1, but little or no toxicity was found with control cells. In contrast to arachidonic acid, oleic acid was not toxic to the HepG2-MV2E1-9 cells. The cytotoxicity of arachidonic acid involved a lipid peroxidation type of mechanism since toxicity was enhanced after depletion of cellular glutathione; formation of malondialdehyde and 4-hydroxy-2-nonenal was markedly elevated in the cells expressing CYP2E1, and toxicity was prevented by antioxidants and the iron chelator desferrioxamine. The CYP2E1-dependent arachidonic acid toxicity appeared to involve apoptosis, as demonstrated by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling and DNA laddering experiments. Trolox, which prevented toxicity of arachidonic acid, also prevented the apoptosis. Transfection with a plasmid containing bcl-2 resulted in complete protection against the CYP2E1-dependent arachidonic acid toxicity. It is proposed that elevated production of reactive oxygen intermediates by cells expressing CYP2E1 can cause lipid peroxidation, which subsequently promotes apoptosis and cell toxicity when the cells are enriched with polyunsaturated fatty acids such as arachidonic acid.

Animals↗